Surgical cross connector

ABSTRACT

Example embodiments relate generally to an apparatus operable to couple a pair of implantation rods that are surgically implanted adjacent to a plurality of vertebrae. Each implantation rod is secured by at least one fastener element having a head. The apparatus comprises at least one main assembly, said main assembly operable to move relative to a head of one of the fastener elements when not in a locked position. The apparatus also comprises a center link extending in an axial direction, said center link operable to move relative to the main assembly when not in a locked position. The main assembly is operable to receive the center link and a head of one of the fastener elements and secure the center link and the head relative to the main assembly when in a locked position.

TECHNICAL FIELD

The present disclosure relates generally to a surgical cross connectingapparatus for use with implantation rods.

BACKGROUND

The spinal column is a highly complex interconnection of individualbones coupled together to provide, among other things, protection of thenervous system, while also enabling collective movements in a pluralityof directions.

Due to various genetic and/or developmental occurrences, includingdiseases, developmental irregularities, trauma, stress, and the like,the spinal column may require surgical intervention. To protect and/oraid in the recovery of a surgically repaired section of the spinalcolumn, there are often situations wherein it is desirable tocollectively restrict movement of one or more bones of the spinalcolumn.

Immobilization of a section of the spinal column may be achieved using avariety of known surgically implanted support systems and methods, suchas use of posterior surgical implants comprising one or moreimplantation rods. In general, a surgically-implanted rod is fixedlyattached by first threading one or more anchor screws to a pedicle ofone or more vertebrae of the spinal column. Each anchor screw is in turnfixedly coupled to the implantation rod at proximate locations along itsshaft.

In certain patients, it may be desirable to increase the support andtorsional rigidity of the surgically-implanted implantation rod system.These situations may require not only support on the side of the spinalcolumn that is attached to an implantation rod, but also torsionalrigidity and support collectively between the implantation rods. Toachieve this, patients have been selectively provided with surgicallyimplanted cross connector systems to couple between two implantationrods.

SUMMARY

Conventional screw head-type cross connector systems, such as those thatsecure two implantation rods by attaching to the head of anchor screws(see U.S. Pat. No. 7,717,939), and hook set-type cross connectorsystems, such as those that secure two implantation rods by attachinghooks to the shaft of the rod (see U.S. Pat. No. 6,238,396), may beemployed to couple two implanted rods in situations wherein theimplantation rods are substantially parallel relative to each other inevery axis (hereinafter “three dimensionally parallel” or “3D parallel”)and have a sufficient separation distance between each other. An exampleof a pair of implantation rods that are three dimensionally parallel isshown in FIG. 1, wherein d represents a minimum separation distancebetween a first implantation rod (100) and a second implantation rod(200) so as to enable a conventional cross connector system to attachbetween the two implantation rods.

Due to their limited adjustability, including providing limited screwhead to screw head length adjustments, conventional screw head-typecross connector systems are generally not suitable for situations wherethe implantation rods are not three dimensionally parallel and/or thereis insufficient separation distance between screw heads (hereinafter“non-ideal situations” or “non-ideal positions”). An example of twoimplantation rods (100, 200) that are not three-dimensionally parallelis shown in FIG. 2. Conventional hook set-type cross connector systemshave been recently introduced to provide a certain degree of freedom toaccommodate more non-ideal situations, particularly those whereconventional screw head-type cross connector systems cannot be employed.However, they too have limitations in use, particularly in thosesituations requiring more degrees of freedom to cross connect innon-ideal situations and/or having insufficient separation distancebetween screw heads.

In general, non-ideal situations frequently occur in patients requiringincreased support and torsional rigidity between sets of bones supportedby implantation rods. Because conventional cross connector systems arebest suited for attaching in substantially ideal situations and certainlimited non-ideal situations, as described earlier, surgeons are moreoften than not faced with having to perform complicated surgicalre-adjustments of the already-implanted implantation rod systems toaccommodate the attaching of conventional cross connectors. Surgicalre-adjustments may include removing hooks, anchor screws, couplingcomponents, and/or implantation rods, and re-threading the anchor screwsand/or re-installing the components in a differentlocation/position/orientation, so as to enable the implantation rods tobe substantially three-dimensionally parallel and/or having sufficientseparation distance between the screw heads.

In practice, surgeons are often faced with practical problems anddifficulties in implanting implantation rods in patients to besubstantially three-dimensionally parallel and having sufficientseparation distance due to, among other things, the anatomically varyingsizes/shapes/orientations of the spinal column and/or the varyingdegrees and/or nature of surgical repairs required and/or rendered tothe spinal column of each particular patient. More often than not,surgeons have little choice other than to implant implantation rods innon-ideal positions relative to each other. This in turn makes itdifficult to properly couple conventional cross-connecting systems tosuch implanted implantation rods, and surgeons are often required toperform complicated surgical re-adjustments of the implanted rods and/oranchor screws to accommodate the conventional cross connector. Ingeneral, a tremendous amount of time, planning, effort, precision, andcosts are incurred since these tasks typically involve, among otherthings, surgically removing one or more anchor screws, couplingcomponents, and/or implantation rods, and surgically re-installing themin such a way as to properly accommodate a substantially ideal positionof the implantation rods, as required by conventional cross connectingsystems.

In considering the above problems, it is recognized herein thatproviding increased support and torsional rigidity between implantationrods that are implanted in non-ideal positions can be achieved withoutthe need to perform surgical re-adjustments of the implantedimplantation rods, coupling components, and/or anchor screws.

Present example embodiments relate generally to an apparatus operable tocouple a pair of implantation rods. Each implantation rod is secured byat least two fastener elements having a head. The apparatus comprises atleast one main assembly, said main assembly operable to move relative toa head of one of the fastener elements when not in a locked position.The apparatus also comprises a center link extending in an axialdirection, said center link operable to move relative to the mainassembly when not in a locked position. The main assembly is operable toreceive the center link and a head of one of the fastener elements andsecure the center link and the head relative to the main assembly whenin a locked position.

In accordance with another example embodiment, an apparatus is operableto fixably couple a pair of implantation rods, wherein each implantationrod is secured by at least two fastener elements. The apparatuscomprises a center link extending in an axial direction and two or moremain assemblies. Each main assembly is operable to receive the centerlink and a head of one of the fastener elements when not in a lockedposition. Each main assembly comprises a main body, a center link clamphaving an adjustable bore and housed within the main body, an outersleeve surrounding at least a portion of the main body, an anchor clamphaving an adjustable portion and proximate to the main body and theouter sleeve, and an adjustment member operable in cooperation with themain body to adjust the adjustable bore and the adjustable portion. Thecenter link is received in the adjustable bore of the center link clampand the head is received in the adjustable portion of the anchor clamp.The center link and the head are securable relative to the main bodywhen the adjustment member is actuated into a locked position.Furthermore, the center link is movable relative to the main body andthe adjustable portion is movable relative to each main body when theadjustment member is actuated from the locked position.

In another exemplary embodiment, an apparatus is operable to couple animplantation rod to a center link, wherein the implantation rod issecured by at least two fastener elements having a head. The apparatuscomprises a main body, a center link clamp having an adjustable bore andhoused within the main body, an outer sleeve surrounding at least aportion of the main body, an anchor clamp having an adjustable portionand proximate to the main body and the outer sleeve, and an adjustmentmember operable in cooperation with the main body to adjust theadjustable bore and the adjustable portion.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumbers indicate like features, and:

FIG. 1 is an example illustration of a pair of implantation rods thatare three-dimensionally parallel;

FIG. 2 is an example illustration of a pair of implantation rods thatare not three-dimensionally parallel;

FIG. 3A is a perspective view of an example embodiment of a crossconnector;

FIG. 3B is an exploded view of an example embodiment of a crossconnector;

FIG. 3C is a perspective view of an example embodiment of a crossconnector coupled to a pair of implantation rods;

FIG. 4A is a perspective view of another example embodiment of a crossconnector;

FIG. 4B is an exploded view of another example embodiment of a crossconnector;

FIG. 4C is a perspective view of another example embodiment of a crossconnector coupled to a pair of implantation rods;

FIG. 5A is a top view of an example embodiment of a cross connectorillustrating a pivoting movement of the center link relative to thefirst and second main assemblies;

FIG. 5B is a top view of an example embodiment of a cross connectorillustrating another pivoting movement of the center link relative tothe first and second main assemblies;

FIG. 6 is a cross sectional view of an example embodiment of a crossconnector having a set screw.

Although similar reference numbers may be used to refer to similarelements for convenience, it can be appreciated that each of the variousexample embodiments may be considered to be distinct variations.

DETAILED DESCRIPTION

The present invention will now be described hereinafter with referenceto the accompanying drawings, which form a part hereof, and whichillustrate example embodiments by which the invention may be practiced.As used in the disclosures and the appended claims, the term “exampleembodiment” does not necessarily refer to a single embodiment, althoughit may, and various example embodiments may be readily combined andinterchanged, without departing from the scope or spirit of the presentinvention. Furthermore, the terminology as used herein is for thepurpose of describing example embodiments only and is not intended to bea limitation of the invention. In this respect, as used herein, the term“in” may include “in” and “on”, and the terms “a”, “an” and “the” mayinclude singular and plural references. Furthermore, as used herein, theterm “by” may also mean “from”, depending on the context. Furthermore,as used herein, the term “if” may also mean “when” or “upon”, dependingon the context. Furthermore, as used herein, the words “and/or” mayrefer to and encompass any and all possible combinations of one or moreof the associated listed items.

Spinal fixation of an implantation rod may be provided by one or morefastener elements, such as an anchor screw, having a head. Typically,one or more anchor screws will be fixedly installed to a pedicle of oneor more vertebrae, and correspondingly fixedly coupled about proximatesections of the shaft of the implantation rod. In many situations, across connector apparatus may be applied between two implantedimplantation rods, particularly when enhanced support and torsionalrigidity is required. Hereinafter, an “implanted anchor screw” willrefer to an anchor screw that has already been fixedly installed to avertebra and an “implanted implantation rod” will refer to animplantation rod that has already been fixedly coupled to one or moreimplanted anchor screws.

Reference is now made to an example embodiment of the cross connector(300) illustrated in FIGS. 3A, 3B and 3C. As shown in FIG. 3A, The crossconnector (300) comprises a first main assembly (310), a second mainassembly (320), and a center link (330) in communication with the firstmain assembly (310) and the second main assembly (320). The first mainassembly (310) may be substantially the same as, and/or a mirrorreflection of, the second main assembly (320), although they may alsocomprise one or more aspects that are oriented, positioned and/oroperated differently so as to accommodate specific implanted anchorscrew and implantation rod arrangements. In other words, exampleembodiments of the cross connector (300) are adaptively adjustable so asto attach in a wide range of non-ideal situations and positions to twoor more implanted implantation rods. An example embodiment of the crossconnector (300) attached to a set of implanted anchor screws andimplantation rods is depicted in FIG. 3C.

As shown in FIG. 3B, each of the main assemblies (310, 320) comprise amain body (311, 321), an anchor clamp (312, 322) having a fixablyadjustable clamp portion (312 c, 322 c) for receiving the head (351) ofan anchor screw (350), a center link clamp (314, 324) having anadjustable bore (314 a, 324 a) for receiving the center link (330), anouter sleeve (313, 323) surrounding at least a portion of the main body(311, 321) housing the center link clamp (314, 324), and a set camassembly (315, 325) comprising a set cam (315 a, 325 a) and a set cammating element (315 b, 325 b) for enabling each main assembly (310, 320)to be brought into and released from a locked position. The center link(330) is preferably an elongated symmetrically-shaped member receivableby the first and second main assemblies (310, 320) in the adjustablebores (314 a, 324 a) of their respective center link clamps (314, 324),and may include one or more center link nubs (331, 332) to restrict themain assemblies (310, 320) from separating from the center link (330)when not in the locked position. The center link (330) may also takeother shapes and forms in other example embodiments, such as elliptical,hexagonal, or other shapes, and may be straight as depicted or curved.It is to be understood by those skilled in the art that actuating to andreleasing from a locked position can be achievable in a variety of ways,including the use of a set screw, or the like. An example embodiment ofa cross connector (400) being provided with set screws (415, 425) isillustrated in FIGS. 4A, 4B and 4C. Hereinafter, example embodiments ofthe cross connector will be described with reference to the crossconnector (300) having set cams (315, 325) of FIGS. 3A, 3B and 3C,although the descriptions will also be equally applicable to exampleembodiments of the cross connector (400) that are provided with setscrews (415, 425), and the like.

With reference to FIG. 3C, and for the purpose of illustrating exemplaryways in which an example embodiment of the cross connector may bepracticed, certain imaginary axes will be hereinafter defined for thefirst main assembly (310) attached to a certain anchor screw (350) of acertain implantation rod (390). It is to be understood that thefollowing discussion of movements of the first main assembly (310) andcenter link (330) are also applicable to other applications andsituations, such as the first main assembly (310) attaching to any otheranchor screw of any other implantation rod that may or may not be in thesame orientation as depicted in the drawings, as well as to the secondmain assembly (320) being attached to any anchor screw of any otherimplantation rod that may or may not be in the same orientation asdepicted in the drawings. Hereinafter, the imaginary axis drawn throughthe axial center of the anchor screw body (350) will be referred to asthe “anchor screw axis” and is labeled as axis D. Furthermore, theimaginary axis drawn through the axial center of the implantedimplantation rod (390) will be referred to as the “implantation rodaxis” and is labeled as axis A. Furthermore, the imaginary axis drawnthrough the axial center of the main body (311) will be referred to asthe “main body axis” and is labeled as axis E. Furthermore, an imaginaryaxis drawn through the axial center of the center link (330) will bereferred to as the “center link axis” and is labeled as axis C.

When not in the locked position, an example embodiment of the crossconnector is provided with a wide degree of freedom of movement aboutthe implantation rod axis A, the anchor screw axis D, the main body axisE, and/or the center link axis C, which enables the cross connector tobe adaptively applied between two or more anchor screw heads coupled toimplantation rods that may or may not be three-dimensionally paralleland/or may or may not have sufficient separation distance, as requiredby conventional cross connector systems.

With reference to the axes depicted in FIG. 3C, in an exemplarynon-ideal situation, the implanted orientation of one or more implantedanchor screws (350, 360, 370, 380) may be rotated about one or more ofthe imaginary axes. When not in the locked position, the cross connector(300) is operable to properly receive the head of these anchor screws inone or more ways, depending on the specific implanted orientation of theimplanted anchor screws. For example, if the orientation of theimplanted anchor screw (350) is rotated relative to the implantation rodaxis, as illustrated by uni-directional arrow A, the screw clamp body(312) can be correspondingly rotated about the first main body (311) ina similar manner so as to provide for the plane of the adjustable clampportion (312 c) of the anchor clamp (312) to be substantially parallelto the plane of the face (351) of the anchor screw head (350). Furtheradjustments, including displacing the first main assembly (310) ineither axial direction along the center link (330), as depicted bybi-directional arrow B, rotating the first main assembly (310) about thecenter link (330), as depicted by axis C, pivoting the center link (330)about the first main body, as depicted by axes E and/or F (see FIGS. 5Aand 5B), and/or pivoting the center link (330) about the second mainbody axis G, can or may need to be affected to properly receive theanchor screw head (351) in the adjustable clamp portion (312 c) of theanchor clamp (312). It is to be understood that correspondingadjustments can be readily made in situations wherein the orientation ofthe implanted anchor screw (350) is rotated in the opposite direction.It is also to be understood that corresponding adjustments can be madeto the second body assembly (320) in view of the orientation of theanchor screw (350). It is also to be understood that, in addition to orin replacement of the said possible orientation of the implanted anchorscrew (350), corresponding adjustments can or may need to be made to thesecond main assembly (320) in relation to orientation rotations of theanchor screw (370). These adjustments to the example embodiment of thecross connector (300) can be readily made by persons ordinarily skilledin the art.

In another example, if the orientation of the implanted anchor screw(350) is rotated in either direction relative the center link axis C,the first main assembly (310) can be correspondingly rotated about thecenter link (330) in a similar manner so as to provide for the plane ofthe adjustable clamp portion (312 c) of the anchor clamp (312) to besubstantially parallel to the plane of the face (351) of the anchorscrew head (350). Further adjustments, including pivoting the centerlink (330) about one of the main assemblies (310, 320), as depicted byaxes E and/or F (see FIGS. 5A and 5B), transposing the first mainassembly (310) in either direction along the center link (330), asdepicted by axis B, rotating the first main assembly (310) about thecenter link axis, as depicted by bi-directional axis C, pivoting thecenter link (330) about the first main body axis E, and/or pivoting thecenter link (330) about the second main body axis G, can or may need tobe affected to properly receive the anchor screw head (351) in theadjustable clamp portion (312 c) of the anchor clamp (312). It is to beunderstood that corresponding adjustments can be made to the second bodyassembly (320) in view of the orientation of the anchor screw (350). Itis also to be understood that, in addition to or in replacement of thesaid possible orientation of the implanted anchor screw (350),corresponding adjustments can or may need to be made to the second mainassembly (320) in relation to orientation rotations of the anchor screw(370). These adjustments to the example embodiment of the crossconnector (300) can be readily made by persons of ordinary skill in theart.

Exemplary adjustments can also be readily made to the orientation and/orposition of example embodiments of the cross connector in othernon-ideal situations, such as in applications wherein the separationdistance between two implanted implantation rods do not allow for thepreviously-described configurations of having the first and second mainassemblies to be applied between the two implanted implantation rods.For example, the cross connector (300) may be operable so as to positionone of the main assemblies (310, 320) on opposite sides of an implantedimplantation rod (390, 395) while still being in communication with theother main assembly through the center link (330). In exampleembodiments, both of the main assemblies (310, 320) may be positioned onopposite sides of the two implantation rods (390, 395) while still beingin communication with each other through the center link (330). Inperforming either of these adjustments, the cross connector (300) isadaptably adjustable to accommodate situations where the separationdistance between two implanted implantation rods (390, 395) would notenable the previously described configurations, as well as conventionalcross connectors, to be applied. These adjustments may also be appliedalong with other adjustments, such as the previously describedadjustments, to properly couple implanted anchor screw(s) (350, 370)that are implanted in non-ideal positions.

After an example embodiment of the cross connector (300) is adjusted soas to allow the adjustable clamp portions (312 c) of each of the firstanchor clamp (312) and second anchor clamp (322) to properly receive theanchor screw heads (351, 371) of the anchor screws (350, 370) coupled tothe implantation rods (390, 395), the cross connector (300) can befixedly coupled to the implantation rods (390, 395) by actuating boththe first and second main assemblies (310, 320) to the locked position.In an example embodiment of the cross connector (300), each of the mainassemblies (310, 320) are actuated to the locked position when theirrespective set cam assembly (315, 325) is turned to the locked position,which causes certain components of the main assembly (310, 320) to bedisplaced from their neutral positions. In the same manner, and withreference to FIG. 4B, each of the main assemblies (410, 420) of crossconnector (400) are actuated to the locked position when theirrespective set screw assembly (415, 425) is turned to the lockedposition, which also causes certain components of the main assembly(410, 420) to be displaced from their neutral position.

FIGS. 5A and 5B are top views of an example embodiment of a crossconnector (300) illustrating a pivoting movement of the center link(330) relative to the main assembly (310). In FIG. 5A, the center link(330) can be positioned such that its axis is disposed at an angle +Fwith respect to the main body axis G. In FIG. 5B, the center link (330)may also be positioned such that its axis is disposed at an angle −Fwith respect to the main body axis G. This angle F may be in the rangeof about +20 degrees to about −20 degrees.

In FIG. 6, a cross-sectional illustration of an example embodiment ofthe cross connector (300) is depicted. When the set screw (315) in FIG.6 is turned to the locked position, the cylindrical body portions (312a, 312 b) of the anchor clamp (312) are driven towards each other. Thisapplies compression to the anchor clamp (312 c) that is mounted to thehead of a screw. As the set screw (315) is driven into the lockedposition, a compressive force is also applied to the sides (314 b, 314c) of the center link clamp (314) that form the adjustable bore (314 a).This causes the center link clamp (314) to compress the diameter of theadjustable bore (314 a), thus locking the center link (330) within themain body (300). Effectively, the openings of both the adjustable clampportion (312 c) of the anchor clamp (312) and the adjustable bore (314a) of the center link clamp (314) become adjustably sized as the setscrew (315) is driven so as to securely hold the anchor screw head (351)and the center link (330) with respect to the main body, respectively.

While various embodiments in accordance with the disclosed principleshave been described above, it should be understood that they have beenpresented by way of example only, and are not limiting. Thus, thebreadth and scope of the invention(s) should not be limited by any ofthe above-described exemplary embodiments, but should be defined only inaccordance with the claims and their equivalents issuing from thisdisclosure. Furthermore, the above advantages and features are providedin described embodiments, but shall not limit the application of suchissued claims to processes and structures accomplishing any or all ofthe above advantages.

Additionally, the section headings herein are provided for consistencywith the suggestions under 37 C.F.R. 1.77 or otherwise to provideorganizational cues. These headings shall not limit or characterize theinvention(s) set out in any claims that may issue from this disclosure.Specifically, a description of a technology in the “Background” is notto be construed as an admission that technology is prior art to anyinvention(s) in this disclosure. Furthermore, any reference in thisdisclosure to “invention” in the singular should not be used to arguethat there is only a single point of novelty in this disclosure.Multiple inventions may be set forth according to the limitations of themultiple claims issuing from this disclosure, and such claimsaccordingly define the invention(s), and their equivalents, that areprotected thereby. In all instances, the scope of such claims shall beconsidered on their own merits in light of this disclosure, but shouldnot be constrained by the headings herein.

What is claimed is:
 1. An apparatus operable to couple a pair ofimplantation rods, wherein each implantation rod is secured by at leasttwo fastener elements having a head, the apparatus comprising: at leastone main assembly operable to move relative to a head of one of thefastener elements when not in a locked position, the main assemblyincluding a main body, and a center link clamp having an adjustable boreand housed within the main body; and a center link extending in an axialdirection, the center link operable to move relative to the mainassembly when not in a locked position; wherein the main assembly isoperable to receive the center link and a head of one of the fastenerelements; wherein the main assembly is operable to secure the centerlink and the head relative to the main assembly when in a lockedposition; wherein the adjustable bore is a throughhole defined in thecenter link clamp; and wherein a portion of the center link clampincluding the throughole is disposed inside the main body.
 2. Theapparatus of claim 1, wherein the main assembly comprises an outersleeve surrounding at least a portion of the main body, an anchor clamphaving an adjustable portion and proximate to the main body and theouter sleeve, and an adjustment member operable in cooperation with themain body to adjust the adjustable bore and the adjustable portion. 3.The apparatus of claim 2, wherein the center link is received by theadjustable bore of the center link clamp and the head is received by theadjustable portion of the anchor clamp.
 4. The apparatus of claim 2,wherein the center link is secured relative to the main body when theadjustment member is actuated into a locked position.
 5. The apparatusof claim 4, wherein the adjustment member is a set cam assembly andwherein the set cam assembly secures the center link when a wall of theadjustable bore is contacted against the center link.
 6. The apparatusof claim 4, wherein the adjustment member is a set screw and wherein theset screw secures the center link when a wall of the adjustable bore iscontacted against the center link.
 7. The apparatus of claim 2, whereinthe head is secured relative to the main body when the adjustment memberis actuated into a locked position.
 8. The apparatus of claim 7, whereinthe adjustment member is a set cam assembly and wherein the set camassembly secures the head when a wall of the adjustable portion iscontacted against the head.
 9. The apparatus of claim 7, wherein theadjustment member is a set screw and wherein the set screw secures thehead when a wall of the adjustable portion is contacted against thehead.
 10. The apparatus of claim 2, wherein the center link is movablerelative to the main body when the adjustment member is actuated from alocked position.
 11. The apparatus of claim 10, wherein the adjustmentmember is a set cam assembly and wherein the center link is movable whena wall of the bore is released by the set cam assembly from contactingthe center link.
 12. The apparatus of claim 10, wherein the adjustmentmember is a set screw and wherein the center link is movable when a wallof the bore is released by the set screw from contacting the centerlink.
 13. The apparatus of claim 2, wherein the main body is movablerelative to the head when the adjustment member is actuated from alocked position.
 14. The apparatus of claim 13, wherein the adjustmentmember is a set cam assembly and wherein the main body is movablerelative to the head when a wall of the set cam assembly is releasedfrom contacting the anchor clamp.
 15. The apparatus of claim 13, whereinthe adjustment member is a set screw and wherein the main body ismovable relative to the head when a wall of the set screw is releasedfrom contacting the anchor clamp.
 16. The apparatus of claim 2, whereinthe center link clamp is disposed in the outer sleeve.
 17. The apparatusof claim 2, wherein the outer sleeve is distinct from the main body. 18.The apparatus of claim 2, wherein the outer sleeve is separable from themain body.
 19. The apparatus of claim 1, wherein the center link clampis distinct from the main body.
 20. The apparatus of claim 1, whereinthe center link clamp is separable from the main body.
 21. The apparatusof claim 1, wherein the center link is operable to be inserted into thethroughhole.
 22. An apparatus operable to fixably couple a pair ofimplantation rods, wherein each implantation rod is secured by at leasttwo fastener elements, the apparatus comprising: a center link extendingin an axial direction; two or more main assemblies, wherein each mainassembly is operable to receive the center link and a head of one of thefastener elements when not in a locked position, each main assemblycomprising: a main body; a center link clamp having an adjustable boreand housed within the main body; an outer sleeve surrounding at least aportion of the main body; an anchor clamp having an adjustable portionand proximate to the main body and the outer sleeve; and an adjustmentmember operable in cooperation with the main body to adjust theadjustable bore and the adjustable portion; wherein the center link isreceived in the adjustable bore of the center link clamp; wherein thehead is received in the adjustable portion of the anchor clamp; whereinthe center link and the head are securable relative to the main bodywhen the adjustment member is actuated into a locked position; whereinthe center link is movable relative to the main body and the adjustableportion is movable relative to each main body when the adjustment memberis actuated from the locked position; wherein the adjustable bore is athroughhole defined in the center link clamp; and wherein a portion ofthe center link clamp including the throughole is disposed inside themain body.
 23. The apparatus of claim 22, wherein the adjustable memberis a set cam assembly and wherein the set cam assembly secures thecenter link when a wall of the adjustable bore is contacted against thecenter link and secures the head when a wall of the adjustable portionis contacted against the head.
 24. The apparatus of claim 22, whereinthe adjustable member is a set screw and wherein the set screw securesthe center link when a wall of the adjustable bore is contacted againstthe center link and secures the head when a wall of the adjustableportion is contacted against the head.
 25. An apparatus operable tocouple an implantation rod to a center link, wherein the implantationrod is secured by at least two fastener elements having a head, theapparatus comprising: a main body; a center link clamp having anadjustable bore and housed within the main body; an outer sleevesurrounding at least a portion of the main body; an anchor clamp havingan adjustable portion and proximate to the main body and the outersleeve; and an adjustment member operable in cooperation with the mainbody to adjust the adjustable bore and the adjustable portion; whereinthe adjustable bore is a throughhole defined in the center link clamp;and wherein a portion of the center link clamp including the througholeis disposed inside the main body.
 26. The apparatus of claim 25, whereinthe center link is received by the adjustable bore of the center linkclamp and the head is received by the adjustable portion of the anchorclamp.
 27. The apparatus of claim 25, wherein the center link issecurable relative to the main body when the adjustment member isactuated into a locked position.
 28. The apparatus of claim 25, whereinthe head is securable relative to the main body when the adjustmentmember is actuated into a locked position.
 29. The apparatus of claim25, wherein the center link is movable relative to the main body whenthe adjustment member is actuated from the locked position.
 30. Theapparatus of claim 25, wherein the main body is movable relative to thehead when the adjustment member is actuated from the locked position.31. The apparatus of claim 25, wherein the adjustment member is a setcam assembly or a set screw.